A vinylic monomer having a tris(trimethylsilyloxy)silyl (“TRIS”) group, such as, for example, tris(trimethylsilyloxy)silylpropyl acrylate, tris(trimethylsilyloxy)-silylpropyl methacrylate, tris(trimethylsilyloxy)-silylpropyl acryalmide, tris(trimethylsilyloxy)-silylpropyl methacrylamide, tris-(trimethylsiloxysilyl) propylvinyl carbamate, or the like, has been widely used in making silicone hydrogel contact lenses, as it can enhance the oxygen permeability of a lens material while giving the lens with clarity and superior lens properties. Moreover, presence of TRIS-containing vinylic monomers may also be important for dissipation of lens folding mark during lens handling. However, most of TRIS-containing vinylic monomers used in the contact lens industry and/or on the market are generally hydrophobic, not compatible with the hydrophilic components of a silicone hydrogel lens formulation, and not suitable for making water-based silicone hydrogel lens formulations. In addition, unpolymerized TRIS-containing vinylic monomers must be removed from molded lenses by using an organic solvent in a lens extraction process. Such lens extraction process increases the production cost and is not environmentally friendly.
Therefore, there is still a need for TRIS-containing vinylic monomers which have adequate solubility in water and can be used in an environmentally-friendly lens production process.